There are many medicament delivery devices on the market that have been developed for self administration of medicament, where one large group is medicament injection devices. Many of these injection devices have been provided with removable needle cover assemblies where the core cover may be a so called Rigid Needle Cover or Rigid Needle Shield (RNS) or a so called Flexible Needle Cover or Flexible Needle Shield (FNS).
These RNS/FNS's are arranged to protect the injection needle before use in order to keep the needle sterile and also protect from unintentional needle sticks. Many of these RNS/FNS's are pushed onto the neck portion of a medicament container, such as a syringe, where the RNS/FNS are provided with an inner cap in contact with the surface of the syringe. The inner cap is preferably of a resilient material, normally rubber that ensures a tight grip and a good seal between the cap and the syringe. However this tight grip entail problem in that it is difficult to remove the RNS/FNS from the syringe in order to perform an injection.
Therefore a number of RNS/FNS removal devices have been developed, which are intended to aid the user in removing the RNS. Documents WO2007/047200, WO 2006/106290 and WO 2005/115508 disclose different solutions to this problem. However, they all include a function where the whole assembly including the RNS and its resilient inner cap, are twisted or rotated manually. This a major drawback since this twisting action if the inner cap very easily causes damage to the injection needles, which usually are thin and easily bendable such that when the RNS is removed, the needle has become so damaged it cannot be used for the injection.
Also, all these solutions require manual action by gripping the shield remover mechanism and performing a number of manual operations such as twisting and pulling and combinations thereof. This is a drawback for all persons with reduced dexterity in their hands as well as reduced motion control. Further, all these solutions require change of grip of the medicament delivery device after removal of the RNS/FNS. This may also be a drawback in that the injection needle now is exposed when the user is to change grip for the subsequent penetration and injection. Not only may the thin needle be damaged during the process, but the user or other persons in the vicinity may be damaged by the exposed needle.
Document WO 2009/019440 discloses an injection device comprising a cap that in order to be removed is rotated turns about the longitudinal axis. During rotation, the needle shield retainer does not rotate relative to a discharge nozzle and the rotational movement of the cap relative to the housing is converted into linear movement of the needle shield retainer away from the exit aperture in the axial direction achieved through engagement of the screw threads so the needle shield is pulled away from the discharge nozzle through the exit aperture into the central boss. After rotation, the user finally pulls the cap away from the housing, the needle shield and the discharge nozzle are not engaged with each other and the cap becomes completely detached from the injection device.
The device according to '440 does not thus twist or rotate the needle shield but a rotational interaction with threaded components causes a linear movement of the needle shield retainer from the exit aperture of the medicament delivery device. However, the solution is complex regarding the number of components required, and still a manual gripping action as described above is required. Again, the user has to change grip after removal of the needle shield with the addressed risks that this may induce.
There is thus a need for solutions that simplify the removal of needle shields from medicament delivery devices, reducing the risk of damaging the needle as well as reducing the risk of injuring persons.